1. Field of the Invention
The invention relates to a direction-changing roller for suspension frames of developing machines for films or photographic paper, in which the strip-like material which is to be developed is guided along a zigzag or meandering path over the suspension frame and the rollers mounted in it. This direction-changing roller comprises a cylindrical roller body on each end of which there is arranged a collar-like flange which has the effect of preventing the strip-like material which is mounted on and runs on the roller from slipping off the adjacent end of the roller.
2. Background of the Information
When two or more lengths of strip-like photographic material are mounted and guided in a zigzag path over a section of a continuous developing machine formed as a suspension frame, the use of mutually coaxially arranged transporting, running or direction-changing rollers results in an inclined path of the strip-like photographic material, which is conducted around the individual rollers over about 180.degree. . This means that the strip-like film material, between its first point of contact with a roller and its last point of contact, i.e. from entry to departure from this roller, is displaced in the direction of the axis of the roller. The extent of the relative movement between the strip-like shape photographic material and the surface of the associated direction-changing roller is dependent on the geometry of the suspension frame, i.e. on the spacing between the spindles of the two axes of the suspension frame the widths of the individual rollers and so on.
In order to compensate for the axial displacement of the strip-shaped photographic material it is known to arrange the rollers arranged at the lower end of the frame in an inclined direction, i.e. to mount them to rotate about axes which are arranged inclined to the vertical plane of the suspension frame and at the same time parallel to one another. Such an arrangement of the lower rollers however not only is complicated and therefore expensive, but can only partially solve the problem of the axial displacement of the strip-shaped photographic material because non-uniformity in the tension of the web and in the transport of the photographic material cannot be compensated easily.